The invention relates to a high refractive index optical management coating that can be used as a light management film (LMF) in a liquid crystal display, particularly an LMF that can be applied or formed in a microstructure replication process.
Microstructure replication in resinous surfaces is of importance in diverse technical fields such as fabrication of traffic signs, in which reflectivity is provided by cube-corner embossed sheeting; the production of Fresnel ophthalmic lens elements and flexible video disks; and the fabrication of brightness enhancement or light management films for liquid crystal displays. Suitable resinous compositions for the replication of microstructures are disclosed in the patent literature. Martens, U.S. Pat. No. 4,576,850 discloses a variety of such compositions. The disclosure of this patent is herein incorporated in its entirety by reference.
Typically, UV-cured acrylate coatings on a polymer film substrate are preferred LMF's because of their fast cure time and good physical properties. However, the refractive index of most acrylate polymers is relatively low. Brominated aromatic acrylate derivatives commonly are used to increase the refractive index as described by Williams, U.S. Pat. No. 5,855,983. However, often there is a limit to how much brominated acrylate derivative can be used before other properties suffer. Typically, it is found very difficult to obtain a useful LMF with refractive index greater than 1.63 using organic materials alone.
There is a need for an optical management coating, particularly an LMF with higher refractive index to improve performance.